and Nitrogen Injection
Bandar Duraya Al-Anazi
King Saud University, Riyadh, Saudi Arabia
The present state of modern industrial development is characterized by the consumption of enormous quantities of
petroleum. It is not used simply for the production of various
fuels and lubricants; with each passing year more and more
petroleu m is u sed for man ufa ct uri ng sy nthe tic ru b b e r,
synthetic fibers, plastics, drugs, and thousands of other products. While demand for petroleum products continuous to
rise, petroleum production worldwide is in a steady decline.
However, new developments in technology and the rise in
world oil prices give promise that substantial portions of
otherwise neglected oil can be recovered. These newtechnical
developments fall under the broad heading of enhanced oil
recovery (EOR). Enhanced oil recovery is a collection of
general methods, each with its own unique capability to
extract the most oil from a particular reservoir. Each has been
investigated rather thoroughly both from a theoretical and
laboratory perspective, as well as in the field.
Over the years, interest in enhanced oilrecovery (EOR) has
been tempered by the increase in oil reserves and production.
Many techniques have been investigated in the laboratory
and the field for improving oil recovery. Historically the
discovery of major oil fields in the world added large
volumes of oil to the worldwide market. In addition, estima tes o f re se r ves fro m res ervoirs in the M id dl e Eas t
increasedsignificantly, leading to the expectation that the oil
supply would be plentiful. Although large volumes of oil
remain in mature reservoirs, the oil will not be produced in
large quantities by EOR processes unless these processes can
compete economically with the cost of oil production from
conventional sources. Thus, as reservoirs age, a dichotomy
exists between the desire to preserve producing wellsfor
potential EOR processes and the lack of economic incentive
because of the existence of large reserves of oil in the world.
During the life of a well, oil recovery has three stages or categories which are:
1-Primary Oil Recovery
2-Secondary Oil Recovery
3-Tertiary Oil Recovery
Enhanced Oil Recovery Techniques
The term enhanced oil recovery (EOR) basically refers to the
recovery ofoil by any method beyond the primary stage of oil
production. It is defined as the production of crude oil from
reservoirs through processes taken to increase the primary
reservoir drive. These processes may include pressure maintenance, injection of displacing fluids, or other methods such
as th erma l tech ni que s. The re f o re, by defini tion, EOR
techniques include all methods that areused to increase
cumulative oil produced (oil recovery) as much as possible.
Enhanced oil recovery can be divided into two major types of
techniques: thermal and non-thermal recovery.
Non-thermal recovery techniques can be broken down into
Pressure Maintenance. M ore complete recovery of oil is
ac hie ved by spe cia l techn olog ical methods. A commonmethod employed today is artificial maintenance of formation pressure. This traditional step for increasing oil recovery
involves the injection of fluid into (or near) an oil reservoir for
the purpose of delaying the pressure decline during oil
production. Pressure maintenance can significantly increase
the amount of economically recoverable oil over that to be
expected with no pressuremaintenance.
Waterflooding. Production can be increased after a decline in
pressure from the water drive or pressure maintenance by a
technique called waterflooding, which is the injection of
water through injection wells to push crude oil toward
producing wells. Water is pumped into the productive layer
at injection pressure through bore holes in a volume equal to
(or greater than) the volume...